1. Field of the Invention
The present invention relates to a moving blade and to a gas turbine using the moving blade.
2. Description of the Related Art
In a gas turbine, a plurality of disks are arranged in the axial direction of a rotary shaft, and in the circumference of each of the disks a plurality of moving blades are circumferentially embedded adjacent to each other. Stationary vanes provided on a casing, which covers the moving blades, are arranged between adjacent rows of moving blades. A high-temperature combustion gas flows over the moving blades and the stationary vanes, to thereby rotatively drive the moving blades. Accordingly, the rotary shaft is rotated to thereby drive, for example, a compressor and a power generator.
Since high-temperature combustion gas is introduced into the gas turbine, the moving blades and the stationary vanes are exposed to high temperature. In order to cope with high temperature, the moving blade assumes the form of a cooled blade in which cooling medium flow paths are formed (as disclosed in, for example, Japanese Patent Application Laid-Open (kokai) Nos. 2002-129905 and H01-63605).
When the rotary shaft of the gas turbine is rotatively driven, the disks provided on the rotary shaft are rotatively driven. At this time, a row of moving blades moves between adjacent rows of stationary vanes provided on the casing, which is disposed around the rotary shaft. When high-temperature combustion gas flows over the moving blades and the stationary vanes, vortexes are generated at trailing ends of the blades and vanes. The vortexes cause a force to act on the blades and vanes in such a manner as to press the blades and vanes toward the front and rear of the gas turbine and toward the respectively adjacent blades and vanes. As a result, the blades and vanes vibrate.
The conventional moving blades have been found to involve the following problem. When the natural frequency of the stationary vanes disposed on the casing coincides with the natural frequency of the moving blades, the moving blades and the stationary vanes resonate, and the magnitude of vibrations of the blades and vanes increases. As a result, high cycle fatigue (HCF) potentially arises in the moving blades and the stationary vanes.